Structural members fabricated from waste materials and method of making the same

ABSTRACT

The structural member and fabrication thereof may be formed by mixing wood products chemically treated for durability and thermoplastics products. The fabrication process may included processing the products to a desired particle size; mixing the particles; processing the mixture in a high intensity processor and then processing the mixture in an extruder to obtain a molten state for forming the structural element in a mold. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a search or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. ProvisionalApplication Serial No. 60/309,039 filed Jul. 30, 2001 and U.S.application Ser. No. 10/206,160, filed Jul. 25, 2002. This is acontinuation-in-part of U.S. patent application Ser. No. 10/206,160 thatis pending.

BACKGROUND OF THE INVENTION

[0002] The present invention generally relates to materials used for thefabrication of structural members. More specifically, the presentinvention relates to processing chemically treated wood products andwood waste and fabricating such products and waste, along with wastethermoplastic, into useful structural members. These chemically treatedwood products, wood waste and waste thermoplastic otherwise must bedisposed, which is expensive and/or difficult.

[0003] Many wooden materials used as structural members must bechemically treated to render the wood suitable for the particular use orpurpose. For example, wooden poles, posts and cross-members used forsupporting utility lines, railroad cross-ties, and signs are usuallypressure treated with creosote oil, which acts as a fungicide, germicideand insecticide to protect those members from various forms of fungal,bacterial and insect attack. Other chemicals are used to accomplishthese purposes.

[0004] The benefits of chemically treated wooden structural members arewell documented. For example, the life expectancy for untreated railroadties installed during 1900 was four to six years. However, the lifeexpectancy for ties treated with coal tar creosote is approximatelythirty years. Nevertheless, because of the tremendous amount of railroadtrack in service, railroads in the United States replace millions ofrailroad ties every year. The life expectancy of a railroad tie remainsrelatively short because the ties are subject to substantialcompressional and impact stresses as train cars travel over the rails.Because the pressure treatment does not penetrate the entire matrix of awooden structural member, cracking of the outside structure can providea pathway for water and microorganisms to invade untreated wood withinthe tie. The wood ultimately rots and deteriorates under train traffic.These same types of problems exist for other creosote treated woodenmembers which, according to the particular use, experience various typesof environmental exposure and are subject to dynamic loading and therelated stresses. Because these members have a limited life span, thereis an ongoing demand for these structural members for application inboth new and existing installations. The demand is aggravated bydiminishing natural resources, including the hardwood from which most ofthese products are manufactured.

[0005] In addition to a supply shortage, an additional problem existsregarding chemically treated wooden members. Because a tremendous numberof these members must be replaced each year, disposal is required forthe removed members. However, because of the chemical treatment of thesemembers with creosote oil and other substances that have been classifiedas hazardous substances, disposal of these items can be difficult andexpensive. Various solutions have been proposed for disposal of thechemically treated wood as opposed to landfill disposal. Railroadcrossties are commonly used for building retaining walls, raised gardensand other landscaping projects. Another proposed solution is to reducethe wooden members to mulch like material and use the material as fuelin wood fired boilers to generate electricity. There have also beenproposals for recycling the wooden members to be reused for the samepurpose. While these proposals seemingly solve two problems at once, todate none have widely been accepted. Part of the problem is thattransporting the used materials for processing is itself prohibitivelyexpensive. Regarding recycling members, the known processes result in alaminated final product that raises concerns about the integrity of themember at the layer boundaries.

[0006] In addition to disposing of chemically treated wooden structures,disposal of plastic structures and plastic waste is an ongoing problem.Plastic structures and plastic waste can be bulky and consume valuablelandfill space. Although the recycling of plastics has been increasing,depending upon the particular application, some plastics are notacceptable.

[0007] The disclosed structural members solve the above problems. Thedisclosed process for manufacturing the structural members may belocated on site or located immediately adjacent to a railroad siding,thereby eliminating or greatly reducing the transportation costs ofother methods. The disclosed structural members may have no layering butrather have a uniform matrix. The disclosed process uses recycledthermoplastics to fabricate the disclosed structural members, therebyhaving the added benefit of providing an alternative used for plasticswhich might otherwise be discarded.

SUMMARY OF THE INVENTION

[0008] The present invention may be directed to a structural memberwhich may be manufactured from previously chemically treated wood orother waste wood, which has the structural integrity to be used as astructural member for utility lines, railroads, pier construction, andother applications where strength may be required, where there may beexposure to bacterial and insect attack, and where long life may benecessary because, among other reasons, repair expense may beprohibitive because of the expense of taking the particular system outof service to effect the repair.

[0009] The present invention further comprises a method of producing thedisclosed structural members from chemically treated wood whichotherwise must be disposed of at considerable expense. Such treated woodmay include wood that has been painted, laminated wood, Formica, utilitypoles and cross-members, railroad ties, etc. The disclosed method mayfurther comprise the processing of the members being replaced, therebyeliminating or reducing the disposal costs for the old structuralmembers. The method of processing may be configured to be mobile,thereby allowing the structural members to be manufactured onsite andreducing or eliminating handling and transportation expenses for thematerials being replaced. The disclosed method may further comprise theuse of recycled thermoplastic, the thermoplastic acting as both a binderand an encapsulator. Both polyethylene and/or polypropylene, as well asother thermoplastics may be used in the process.

[0010] These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 illustrates a flow diagram outlining the disclosed methodand shows a resulting product according to an embodiment of theinvention.

DETAILED DESCRIPTION

[0012] The following detailed description represents the best currentlycontemplated modes for carrying out the invention. The description isnot to be taken in a limiting sense, but is made merely for the purposeof illustrating the general principles of the invention.

[0013] Referring now to FIG. 1, waste wood, such as chemically-treatedrailroad ties utility poles, etc., may be placed within a grinder 10 orchipper to obtain a chip size ranging from one to forty millimeters indiameter, the grinder 10 or chipper may be of the type which may beportable and towable. The ideal chip size may range from ten to fortymillimeters. One suitable grinder may be a CBI Magnum Force Series 6000Hz Hog manufactured by Continental Bio-Mass Industries, Inc.

[0014] Waste thermoplastic, including polyethylene and/or polypylene orother readily available thermoplastic may also be chipped to obtain achip or particle size ranging from one to twenty millimeters indiameter. Thermoplastics soften when heated, but harden when cooled.Plastic drums, containers, and plastic structures may be processedthrough a chipper 20 machine to obtain the desired chip or particlesize. Depending upon the thermoplastic, instead of a chipper, adensifyer may be used to cause the plastic to consolidate into thedesired particle size. For example, plastic shopping bags cannot bechipped and may instead be processed with a densifyer to consolidate theplastic and obtain plastic particles. The thermoplastic chips may act asbinder and as an encapsilator of the wood chips contained within thematrix of the new structural member.

[0015] After the desired range of chip sizes has been achieved for thewaste wood and the waste thermoplastic, the plastic chips and wood chipsmay be mixed together, such as in a conventional drum mixer 30. Anacceptable mix ratio may be ten to seventy percent-by-weight plasticcorresponding to thirty to ninety percent-by-weight wood chips.

[0016] The resulting mixture from the mixer 30 may then be fed into ahigh-speed blender also known as a high intensity processor 40. Anacceptable high-speed blender may be that manufactured by LexTechnologies, Inc. of Ontario, Canada. The high-speed blender may havehigh-speed blades that may impart a shearing force to the mixture thatimparts friction to the wood and plastic chips, which may thoroughly mixthe wood and plastic chips together and heat up the chip mixture by thefriction of the blades. The heated thermoplastic chips, becoming softer,fill the interstitial space between the wood chips, forming a bindingagent for adjacent wood chips. In addition the high-speed blender mayfurther reduce the size of the wood chips and plastic chips, resultingin a more consolidated and cohesive mixture.

[0017] After the desired consistency is achieved with the high-speedblender, the mixture may be fed into an extruder 50 that may be of theram or single or twin screw type having the capability to heat thebarrel. The extruder 50 compresses the mixture, thereby heating themixture to a temperature in a range from 150 degrees to 275 degreesCentigrade. A molten mixture may be pumped or pulled from the extruder50 into molds that are specially prepared according to the specific sizeand shape of the member required. Following cooling, the plastic-woodmembers may be removed from the molds, inspected, stored for curing andthen installed as desired. The new structural members may have a uniformdispersion of creosote oil or other substance that were used fortreating the source wood, showing a further benefit of the disclosedinvention. As discussed above, because pressure treatment is unable toreach the core of the wooden members with the treating substance, woodenmembers may be vulnerable to fungal, bacterial and insect attack if theinner untreated core is exposed through fracturing or cracking. However,the members formed through the disclosed process may take advantage ofany prior treatment compounds used in the source wood and equallydispense those compounds throughout the new structure. If desired,additional treatment chemicals may be added during the mixing stage toachieve desired properties. For example, in addition to creosote oil, itmay be desirable to add fire retardant or other substances.

[0018] Various molds may be used to form structural members depending onthe form to be produced. Additionally, reinforcement elements may beincluded in a mold for structural strength of the produced structuralmember. Vehicle tire treads that may be waste from discarded or usedtires may be cut into long strips of 1 to 8 inches in width and 5 to 10feet in length for use as a reinforcement element. If longer lengthreinforcement elements may be desired, the tire tread strips may beattached end-to-end by use of an attachment device as of example by usedof metal staples, wires and the like. The tire tread strips may bedisposed in a mold and may extend the full length of the mold. Themolten mixture may be released from the extruder 50 into the mold tosurround the reinforcement element.

[0019] Other reinforcement elements may be used with a structuralmember. For example, where a thin structural element may be formed suchas a plant stake or grape stake, a piece of metal rebar, scalloped wireor the like may be disposed in a mold prior to deposit of the moltenmixture therein. For larger structural elements, railroad rails may beused as the reinforcement elements and one or more disposed in a moldprior to the molten mixture being released into the mold to surround thereinforcement elements. Use of discarded tires, rebar, wire, railroadrails and the like may aid in reducing environmental problems; however,new materials for reinforcement elements may also be used in theprocess.

[0020] Additional elements may be added during the mixing process. Abaking soda may be added to the plastic chips and wood chips in themixer 30 in a 1 to 3 percent by weight ratio of the total mixture. Thebaking soda may act as an emulsifier. Further, an ultraviolet or UVprotection material may be mixed with the other element in the mixer 30in a 1 to 4 percent by weight ratio of the total mixture. Theultraviolet protection material may be a black color concentrate such asproduced by AMPACET.

[0021] While the invention has been particularly shown and describedwith respect to the illustrated embodiments thereof, it will beunderstood by those skilled in the art that the foregoing and otherchanges in form and details may be made therein without departing fromthe spirit and scope of the invention.

I claim:
 1. A method for manufacture of structural members from existingwood and thermoplastic products and materials comprising: selecting awood product that has been chemically treated for durability; processingsaid wood product in a grinder to form chemically treated woodparticles; selecting a thermoplastic and processing said thermoplasticin a chipper to form thermoplastic particles; mixing said chemicallytreated wood particles and said thermoplastic particles in a mixer toform a mixture; processing said mixture in a high intensity processor tofurther mix and preheat said mixture; processing said mixture in anextruder to compress and heat said mixture to form a molten mixture;placing said molten mixture into a mold for forming a structural member;and removing from said mold after cooling has occurred said structuralmember.
 2. The method as in claim 1 wherein said wood product chemicaltreatment is creosote oil.
 3. The method as in claim 1 wherein said woodproduct is selected from the group of a wood railroad tie, a woodutility pole and a wood sign post.
 4. The method as in claim 1 whereinsaid thermoplastic is selected from the group of a polyethylene and apolypropylene.
 5. The method as in claim 1 wherein said chemicallytreated wood particles are processed to a size to be a diameter ofapproximately one to forty millimeters.
 6. The method as in claim 1wherein said thermoplastic particles are processed to a size to be adiameter of approximately one to twenty millimeters.
 7. The method as inclaim 1 wherein processing said thermoplastic is performed in adensifier.
 8. The method as in claim 1 wherein said wood product is awaste material.
 9. The method as in claim 1 wherein said thermoplasticis a waste material.
 10. The method as in claim 1 wherein said mixtureis comprised of approximately ten to seventy percent by weight of saidthermoplastic and approximately thirty to ninety percent by weight ofsaid wood product.
 11. The method as in claim 1 wherein processing issaid high intensity processor further reduces the size of saidthermoplastic particles and said chemically treated wood particles. 12.The method as in claim 1 wherein said extruder heats said mixture toapproximately a temperature of 150 degrees Centigrade to 230 degreesCentigrade.
 13. The method as in claim 1 further comprising the addingof a fire retardant substance during said mixing.
 14. The method as inclaim 1 further comprising the adding of a baking soda of approximatelyone to three percent by weight of said mixture during said mixing. 15.The method as in claim 1 further comprising the adding of an ultravioletprotection material of approximately one to four percent by weight ofsaid mixture during said mixing.
 16. The method as in claim 1 furthercomprising the disposing of a reinforcement element in said mold priorto placing said molten mixture in said mold.
 17. The method as in claim16 wherein said reinforcement element is selected from the group of atire tread strip, a rebar, a wire and a railroad rail.
 18. A structuralmember produced according to the method of claim
 1. 19. A method formanufacture of structural members from existing wood and thermoplasticproducts and materials, comprising the steps of: selecting a woodproduct that has been chemically treated for durability; processing saidwood product in a grinder to form chemically treated wood particles of adiameter of approximately one to forty millimeters; selecting athermoplastic and processing said thermoplastic in a chipper to formthermoplastic particles of a diameter of approximately one to twentymillimeters; mixing said chemically treated wood particles and saidthermoplastic particles in a mixer to form a mixture comprised ofapproximately ten to seventy percent by weight of said thermoplastic andapproximately thirty to ninety percent by weight of said wood product;mixing a baking soda comprised of approximately one to three percent byweight of said mixture and an ultraviolet protection material comprisedof approximately one to four percent by weight of said mixture in saidmixture; processing said mixture in a high intensity processor tofurther mix and preheat said mixture; processing said mixture in anextruder to compress and heat said mixture to approximately atemperature of 150 degrees Centigrade to 230 degrees Centigrade to forma molten mixture; disposing a reinforcement element in a mold; placingsaid molten mixture into said mold for forming a structural member; andremoving from said mold after cooling has occurred said structuralmember.
 20. A structural member produced according to the method ofclaim
 19. 21. A structural member comprising: a mixture of a woodproduct chemically treated for durability and a thermoplastic; whereinsaid mixture is comprised of approximately ten to seventy percent byweight of said thermoplastic and approximately thirty to ninety percentby weight of said wood product; and wherein said mixture has beencompressed and heated to allow said thermoplastic to penetrate in saidwood product having molds therein.
 22. The structural member as in claim21 wherein said wood products are chemically treated with creosote oil.23. The structural member as in claim 21 wherein a reinforcement elementis disposed in said structural member.
 24. The structural member as inclaim 21 wherein said mixture is further comprised of a baking soda ofapproximately one to three percent by weight of said mixture.
 25. Thestructural member as in claim 21 wherein said mixture is furthercomprised of an ultraviolet protection material of approximately one tofour percent by weight of said mixture.